The objectives of this research are to explore the relationships of cellular and humoral immunity in regards to immunogenicity of sperm and the effects of immunization with sperm or sperm antigens on fertility in mice. Inbred strains of mice will be used to assure adequate genetic control and reproducibility of results. Immunogenicity of sperm will be enhanced by cooperativity, in which antigens other than sperm associated ones will be coupled to sperm. An investigation of the supressive effects of sperm themselves and particularly seminal plasma on various forms of immunity will be examined. We plan to study these suppressive effects in a variety of cellular and humoral immune assays in vivo and in vitro. A suppressive factor identified in seminal plasma will be purified and characterized. This work will attempt to explain the low natural immunogenicity of sperm and develop possible means for inducing infertility by immunological means. BIBLIOGRAPHIC REFERENCES: Stites, D.P. and Erickson, R.P. Suppressive Effect of Seminal Plasma on Lymphocyte Activation. Nature (London) 253: 727, 1975. Erickson, R.P. and Stites, D.P. Effects of Murine Spermatozoa on Mixed Leukocyte Reaction. Transplantation 20: 263, 1975.